Hydrogen generating fuel cell cartridges

ABSTRACT

A gas-generating apparatus includes a reaction chamber having a first reactant, a reservoir having an optional second reactant, and a self-regulated flow control device. The self-regulated flow control device stops the flow of reactant from the reservoir to the reaction chamber when the pressure of the reaction chamber reaches a predetermined level. Methods of operating the gas-generated apparatus and the self-regulated flow control device, including the cycling of a shut-off valve of the gas-generated apparatus and the cycling of the self-regulated flow control device are also described.

CROSS-REFERENCED TO RELATED APPLICATION

The present application is a continuation application of U.S. patentapplication Ser. No. 12/359,442, filed on Jan. 26, 2009, and is now U.S.Pat. No. 8,118,893, which is a continuation application of U.S. patentapplication Ser. No. 11/067,167, filed on Feb. 25, 2005, and is now U.S.Pat. No. 7,481,858. The '442 and '167 applications are incorporated byreference herein in their entirety.

BACKGROUND OF THE INVENTION

Fuel cells are devices that directly convert chemical energy ofreactants, i.e., fuel and oxidant, into direct current (DC) electricity.For an increasing number of applications, fuel cells are more efficientthan conventional power generation, such as combustion of fossil fuel,as well as portable power storage, such as lithium-ion batteries.

In general, fuel cell technology includes a variety of different fuelcells, such as alkali fuel cells, polymer electrolyte fuel cells,phosphoric acid fuel cells, molten carbonate fuel cells, solid oxidefuel cells and enzyme fuel cells. Today's more important fuel cells canbe divided into several general categories, namely (i) fuel cellsutilizing compressed hydrogen (H₂) as fuel; (ii) proton exchangemembrane (PEM) fuel cells that use alcohols, e.g., methanol (CH₃OH),metal hydrides, e.g., sodium borohydride (NaBH₄), hydrocarbons, or otherfuels reformed into hydrogen fuel; (iii) PEM fuel cells that can consumenon-hydrogen fuel directly or direct oxidation fuel cells; and (iv)solid oxide fuel cells (SOFC) that directly convert hydrocarbon fuels toelectricity at high temperature.

Compressed hydrogen is generally kept under high pressure and istherefore difficult to handle. Furthermore, large storage tanks aretypically required and cannot be made sufficiently small for consumerelectronic devices. Conventional reformat fuel cells require reformersand other vaporization and auxiliary systems to convert fuels tohydrogen to react with oxidant in the fuel cell. Recent advances makereformer or reformat fuel cells promising for consumer electronicdevices. The most common direct oxidation fuel cells are direct methanolfuel cells or DMFC. Other direct oxidation fuel cells include directethanol fuel cells and direct tetramethyl orthocarbonate fuel cells.DMFC, where methanol is reacted directly with oxidant in the fuel cell,is the simplest and potentially smallest fuel cell and also haspromising power application for consumer electronic devices. SOFCconvert hydrocarbon fuels, such as butane, at high heat to produceelectricity. SOFC requires relatively high temperature in the range of1000° C. for the fuel cell reaction to occur.

The chemical reactions that produce electricity are different for eachtype of fuel cell. For DMFC, the chemical-electrical reaction at eachelectrode and the overall reaction for a direct methanol fuel cell aredescribed as follows:

Half-Reaction at the Anode:CH₃OH+H₂O→CO₂+6H⁺+6e ⁻

Half-Reaction at the Cathode:1.5O₂+6H⁺+6e ⁻→3H₂O

The Overall Fuel Cell Reaction:CH₃OH+1.5O₂→CO₂+2H₂O

Due to the migration of the hydrogen ions (H⁺) through the PEM from theanode to the cathode and due to the inability of the free electrons (e⁻)to pass through the PEM, the electrons flow through an external circuit,thereby producing an electrical current through the external circuit.The external circuit may be used to power many useful consumerelectronic devices, such as mobile or cell phones, calculators, personaldigital assistants, laptop computers, and power tools, among others.

DMFC is discussed in U.S. Pat. Nos. 5,992,008 and 5,945,231, which areincorporated herein by reference in their entireties. Generally, the PEMis made from a polymer, such as Nafion® available from DuPont, which isa perfluorinated sulfonic acid polymer having a thickness in the rangeof about 0.05 mm to about 0.50 mm, or other suitable membranes. Theanode is typically made from a Teflonized carbon paper support with athin layer of catalyst, such as platinum-ruthenium, deposited thereon.The cathode is typically a gas diffusion electrode in which platinumparticles are bonded to one side of the membrane.

In another direct oxidation fuel cell, borohydride fuel cell (DBFC)reacts as follows:

Half-Reaction at the Anode:BH₄−+8OH−→BO₂−+6H₂O+8e−

Half-Reaction at the Cathode:2O₂+4H₂O+8e−→8OH−

In a chemical metal hydride fuel cell, aqueous sodium borohydride isreformed and reacts as follows:NaBH₄+2H₂O→(heat or catalyst)→+4(H₂)+(NaBO₂)

Half-Reaction at the Anode:H₂→2H⁺+2e ⁻

Half-Reaction at the Cathode:2(2H⁺+2e ⁻)+O₂→2H₂O

Suitable catalysts for this reaction include platinum and ruthenium, andother metals. The hydrogen fuel produced from reforming sodiumborohydride is reacted in the fuel cell with an oxidant, such as O₂, tocreate electricity (or a flow of electrons) and water byproduct. Sodiumborate (NaBO₂) byproduct is also produced by the reforming process. Asodium borohydride fuel cell is discussed in U.S. Pat. No. 4,261,956,which is incorporated herein by reference in its entirety.

One of the most important features for fuel cell application is fuelstorage. Another important feature is to regulate the transport of fuelout of the fuel cartridge to the fuel cell. To be commercially useful,fuel cells such as DMFC or PEM systems should have the capability ofstoring sufficient fuel to satisfy the consumers' normal usage. Forexample, for mobile or cell phones, for notebook computers, and forpersonal digital assistants (PDAs), fuel cells need to power thesedevices for at least as long as the current batteries and, preferably,much longer. Additionally, the fuel cells should have easily replaceableor refillable fuel tanks to minimize or obviate the need for lengthyrecharges required by today's rechargeable batteries.

One disadvantage of the known hydrogen gas generators is that once thereaction starts the gas generator cartridge cannot control the reaction.Thus, the reaction will continue until the supply of the reactants runout or the source of the reactant is manually shut down.

Accordingly, there is a desire to obtain a hydrogen gas generatorapparatus that is capable of self-regulating the flow of at least onereactant into the reaction chamber.

SUMMARY OF THE INVENTION

The present invention is directed to fuel systems/gas-generatingapparatus that have significantly longer shelf life and are moreefficient in producing hydrogen.

In one embodiment, the present invention relates to a gas-generatingapparatus that includes at least a reaction chamber, a reservoir and aself-regulated flow control device or system. The self-regulated flowcontrol device/system stops the transport of the reactant from thereservoir to the reaction chamber when the pressure inside the reactionchamber reaches a predetermined pressure.

In another embodiment, the gas-generating apparatus of the presentinvention includes a reaction chamber and a reservoir containing atleast one reactant. The reactant is transported from the reservoir tothe reaction chamber to generate hydrogen gas. Generally, when thepressure in the reaction chamber exceeds a predetermined pressure, theapparatus switches from an operative state to a non-operative state, andwhen the pressure drops below the predetermined pressure, the apparatusswitches from a non-operative state to an operative state.

Preferably, the reaction chamber contains another reactant or acatalyst, or is heated to promote the production of hydrogen gas. Thereactant from the reservoir can be transported by capillary action or bya pump. The reservoir may also be pressurized by different methods totransport the reactant from the reservoir to the reaction chamber.Alternatively, the pressure created by the reforming reaction in thereaction chamber can be communicated back to the reservoir to transportthe reactant to the reaction chamber.

The self-regulated flow control device can be a pressure sensitivediaphragm, a check valve, a piston or pusher, a means to discontinue thecapillary flow path, among others, or combinations thereof.

Methods of operating the gas-generated apparatus and the self-regulatedflow control device, including the cycling of a shut-off valve of thegas-generated apparatus and the cycling of the self-regulated flowcontrol device are also provided.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide a further explanation of the presentinvention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which form a part of the specification andare to be read in conjunction therewith and in which like referencenumerals are used to indicate like parts in the various views:

FIG. 1( a) is a cross-sectional view of a gas-generating apparatushaving a self-regulated flow control device in an operative state; FIG.1( b) is a cross-sectional view of a gas-generating apparatus of FIG. 1(a) in a non-operative state; FIG. 1( c) is a schematic view of analternate self-regulated flow control device usable in thegas-generating apparatus illustrated in FIG. 1( a), wherein thealternative self-regulated flow control device is in a non-operativestate; FIG. 1( d) is a schematic view of the alternate self-regulatedflow control device of FIG. 1( c) in an operative state;

FIG. 2( a) is a cross-sectional view of another gas-generating apparatushaving a self-regulated flow control device; FIGS. 2( b)-(d) areschematic views of different wafers and sprayer attachments suitable foruse with the gas-generating apparatus of FIG. 2( a);

FIG. 3 is a cross-sectional view of an alternate gas-generatingapparatus having a pusher to start the initial reaction;

FIG. 4( a) is a cross-sectional view of another gas-generatingapparatus; FIGS. 4( b) and 4(c) illustrate the flow control device ofthe gas-generating apparatus of FIG. 4( a) in a open and closedposition, respectively;

FIGS. 5( a) and 5(b) show variations of the embodiment of FIG. 4( a);

FIG. 6 is a cross-sectional view of another gas-generating apparatus;

FIG. 7 is a cross-sectional view of another gas-generating apparatushaving a rotating rod that can be utilized to start a reaction;

FIG. 8( a) is a cross-sectional view of another gas-generating apparatushaving a push button to start the reaction; FIGS. 8( b)-8(d) are partialcut-away schematic views illustrating different starting mechanismsusable with the gas-generating apparatus of FIGS. 3 and 8( a);

FIG. 9( a) is a cross-sectional view of another gas-generating apparatushaving a self-regulated flow control device that can include adiaphragm; FIG. 9( b) is an enlarged cross-sectional view of theself-regulated flow control device of FIG. 9( a); FIG. 9( c) is anenlarged cross-sectional view of the self-regulated flow control deviceof FIG. 9( a) when the self-regulated flow control device is in a closedposition; FIG. 9( d) is an enlarged cross-sectional view of theself-regulated flow control device of FIG. 9( a) when the self-regulatedflow control device is in an open position;

FIG. 10 is a cross-sectional view of another gas-generating apparatus;and

FIG. 11 is a partial cross-sectional view of a baffle or ventingmechanism usable to minimize the build up of partial pressure within thereactant reservoir.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As illustrated in the accompanying drawings and discussed in detailbelow, the present invention is directed to a fuel supply, which storesfuel cell fuels, such as methanol and water, methanol/water mixture,methanol/water mixtures of varying concentrations, pure methanol, and/ormethyl clathrates described in U.S. Pat. Nos. 5,364,977 and 6,512,005B2, which are incorporated herein by reference in their entirety.Methanol and other alcohols are usable in many types of fuel cells,e.g., DMFC, enzyme fuel cells and reformat fuel cells, among others. Thefuel supply may contain other types of fuel cell fuels, such as ethanolor alcohols; metal hydrides, such as sodium borohydrides; otherchemicals that can be reformatted into hydrogen; or other chemicals thatmay improve the performance or efficiency of fuel cells. Fuels alsoinclude potassium hydroxide (KOH) electrolyte, which is usable withmetal fuel cells or alkali fuel cells, and can be stored in fuelsupplies. For metal fuel cells, fuel is in the form of fluid borne zincparticles immersed in a KOH electrolytic reaction solution, and theanodes within the cell cavities are particulate anodes formed of thezinc particles. KOH electrolytic solution is disclosed in United Statespublished patent application no. 2003/0077493, entitled “Method of UsingFuel Cell System Configured to Provide Power to One or More Loads,”published on Apr. 24, 2003, which is incorporated herein by reference inits entirety. Fuels can also include a mixture of methanol, hydrogenperoxide and sulfuric acid, which flows past a catalyst formed onsilicon chips to create a fuel cell reaction. Moreover, fuels include ablend or mixture of methanol, sodium borohydride, an electrolyte, andother compounds, such as those described in U.S. Pat. Nos. 6,554,877;6,562,497; and 6,758,871, which are incorporated herein by reference intheir entireties. Furthermore, fuels include those compositions that arepartially dissolved in a solvent and partially suspended in a solvent,described in U.S. Pat. No. 6,773,470 and those compositions that includeboth liquid fuel and solid fuels, described in United States publishedpatent application no. 2002/0076602. These references are alsoincorporated by reference in their entireties.

Fuels can also include a metal hydride such as sodium borohydride(NaBH₄) and water, discussed above. Fuels can further includehydrocarbon fuels, which include, but are not limited to, butane,kerosene, alcohol, and natural gas, as set forth in United Statespublished patent application no. 2003/0096150, entitled “LiquidHereto-Interface Fuel Cell Device,” published on May 22, 2003, which isincorporated herein by reference in its entirety. Fuels can also includeliquid oxidants that react with fuels. The present invention istherefore not limited to any type of fuels, electrolytic solutions,oxidant solutions or liquids or solids contained in the supply orotherwise used by the fuel cell system. The term “fuel” as used hereinincludes all fuels that can be reacted in fuel cells or in the fuelsupply, and includes, but is not limited to, all of the above suitablefuels, electrolytic solutions, oxidant solutions, gaseous, liquids,solids, and/or chemicals and mixtures thereof.

As used herein, the term “fuel supply” includes, but is not limited to,disposable cartridges, refillable/reusable cartridges, containers,cartridges that reside inside the electronic device, removablecartridges, cartridges that are outside of the electronic device, fueltanks, fuel refilling tanks, other containers that store fuel and thetubings connected to the fuel tanks and containers. While a cartridge isdescribed below in conjunction with the exemplary embodiments of thepresent invention, it is noted that these embodiments are alsoapplicable to other fuel supplies and the present invention is notlimited to any particular type of fuel supply.

The fuel supply of the present invention can also be used to store fuelsthat are not used in fuel cells. These applications can include, but arenot limited to, storing hydrocarbons and hydrogen fuels for microgas-turbine engine built on silicon chips, discussed in “Here Come theMicroengines,” published in The Industrial Physicist (December2001/January 2002) at pp. 20-25. As used in the present application, theterm “fuel cell” can also include microengines. Other applications caninclude storing traditional fuels for internal combustion engines andhydrocarbons, such as butane for pocket and utility lighters and liquidpropane.

Suitable known hydrogen generating apparatus are disclosed incommonly-owned, co-pending U.S. patent application Ser. Nos. 10/679,756and 10/854,540. The disclosure of these references is incorporatedherein by reference in their entireties.

In various embodiments of the present invention, the gas-generatingapparatus of the present invention may include a reaction chamber and areservoir having a second reactant. The reaction chamber can include anoptional first reactant. The first and second reactants can be a metalhydride, e.g., sodium borohydride and water. Both reactants can be ingaseous, liquid, aqueous or solid form. Preferably, the first reactantstored in the reaction chamber is a solid metal hydride or metalborohydride, and the second reactant is water optionally mixed withadditives and catalysts. One of the reactants may include methylclathrates, which essentially include methanol enclosed or trappedinside other compounds. Water and metal hydride of the present inventionreact to produce hydrogen gas, which can be consumed by a fuel cell toproduce electricity. Other suitable reactants or reagents are disclosedin Ser. No. 10/854,540, previously incorporated above.

Additionally, the gas-generating apparatus can include a device orsystem that is capable of controlling the transport of a second reactantfrom the reservoir to the reaction chamber. The operating conditionsinside the reaction chamber and/or the reservoir, preferably a pressureinside the reaction chamber, are capable of controlling the transport ofthe second reactant in the reservoir to the reaction chamber. Forexample, the second reactant in the reservoir can be introduced into thereaction chamber when the pressure inside the reaction chamber is lessthan a predetermined value, preferably less than the pressure in thereservoir, and, more preferably less than the pressure in the reservoirby a predetermined amount. It is preferable that the flow of the secondreactant from the reservoir into the reaction chamber is self-regulated.Thus, when the reaction chamber reaches a predetermined pressure,preferably a predetermined pressure above the pressure in the reservoir,the flow of the second reactant from the reservoir into the reactionchamber can be stopped to stop the production of hydrogen gas.Similarly, when the pressure of the reaction chamber is reduced belowthe pressure of the reservoir, preferably below the pressure in thereservoir by a predetermined amount, the second reactant can flow fromthe reservoir into the reaction chamber. The second reactant in thereservoir can be introduced into the reaction chamber by any knownmethod including, but not limited to, pumping, osmosis, capillaryaction, pressure differential, valve(s), or combinations thereof.

As illustrated in FIG. 1( a), the gas-generating apparatus can include areaction chamber 12 having a first reactant, a reservoir 14 having asecond reactant, a self-regulated flow control device 16, and a conduit18. Alternatively, reaction chamber 12 may contain a catalyst instead ofa reactant, or reaction chamber 12 can be heated. Conduit 18 includes afirst end located within reservoir 14 and an opposite second end capableof being removably connected to, or operatively associated to, reactionchamber 12. When the first reactant and the second reactant are mixedtogether, they react to produce hydrogen gas.

To reduce the chance of a partial vacuum forming in reservoir 14, anexpanding substance can be inserted into reservoir 14 so that asreactant is transported the expanding substance at least partiallyreplaces the transported volume. Suitable expanding materials include,but are not limited to, butane, alcohols such as methanol, pressurizedballoons, among others. Alternately, a relief valve can be placed incommunication with reservoir 14 to let air to enter as reactant istransported out of reservoir 14. Another device to minimize thedevelopment of a partial vacuum is discussed below. These devices areusable with any embodiments in the present invention.

Gas-generating apparatus 10 can also have an orientation device, such asmass 20, attached to a portion of conduit 18 to ensure that the firstend of conduit 18 is in a fluid communication with the second reactantin reservoir 14. The mass can include any weight that is capable ofmoving the first end of conduit 18 to the location where the secondreactant is accumulated or is located, regardless of the orientation ofapparatus 10. Hence, as reactant is withdrawn from reservoir 14, thelevel of the liquid reactant decreases in reservoir 14, first end ofconduit 18 needs to be in contact with the second reactant regardless ofhow apparatus 10 is positioned, e.g., sideway, diagonal or upside-down.In other words, mass 20 and the remaining reactant are pulled by gravityin the same direction thereby maintaining contact. The second end ofconduit 18 is preferably enlarged, as shown, to more efficientlydistribute the second reactant before it enters reaction chamber 12.

Conduit 18 can be made from any material capable of transporting thesecond reactant in reservoir 14 to reaction chamber 12. Preferably,conduit 18 can include any material or design that is capable of wickingliquid or providing capillary action. Suitable conduit materialsinclude, but are not limited to, fibers, fillers, fibrous materials,open-celled foams, sand materials, or a combination thereof. Preferably,conduit 18 is flexible. Conduit 18 can have any shape that is capable oftransporting the second reactant to reaction chamber 12. Conduit 18 mayalso comprises one or more wicking members embedded within animpermeable sheath or a solid block.

Optionally, gas-generating apparatus 10 may not include conduit 18 ifgas-generating apparatus 10 is primarily utilized in a position ororientation wherein the second reactant from reservoir 14 can beintroduced into reaction chamber 12 without conduit 18 by gravity feed.

Gas-generating apparatus 10 may also include layer 24 disposed betweenreaction chamber 12 and reservoir 14. Layer 24 has a porous surface andcould be made from any material capable of evenlydistributing/introducing the second reactant to the first reactant.Layer 24 is preferably a wicking material similar to conduit 18.

Furthermore, gas-generating apparatus 10 can include an optional liquidimpermeable, gas permeable layer/membrane 25 that allows the passage ofgases, such as hydrogen gas, out of the apparatus, and at the same timekeeps liquid within reaction chamber 12. Membrane 25 can be made of anyliquid impermeable, gas permeable material known to one skilled in theart. Such materials can include, but are not limited to, hydrophobicmaterials having an alkane group. More specific examples include, butare not limited to: polyethylene compositions, polytetrafluoroethylene,polypropylene, polyglactin (VICRY®), lyophilized dura mater, orcombinations thereof. Gas permeable member 25 may also comprise a gaspermeable/liquid impermeable membrane covering a porous member. Examplesof such membrane are CELGARD® and GORE-TEX®. Other gas permeable, liquidimpermeable members usable in the present invention include, but are notlimited to, SURBENT® Polyvinylidene Fluoride (PVDF) having a porous sizeof from about 0.1 μm to about 0.45 μm, available from MilliporeCorporation. The pore size of SURBENT® PVDF regulates the amount ofwater exiting the system. Materials such as electronic vent typematerial having 0.2 μm hydro, available from W. L. Gore & Associates,Inc., can also be used in the present invention. Additionally, 0.25 inchdiameter rods having a pore size of about 10 μm or 2 inch diameter discswith a thickness of about 0.3 μm available from GenPore, and sinteredand/or ceramic porous material having a pore size of less than about 10μm available from Applied Porous Technologies Inc. are also usable inthe present invention. Furthermore, nanograss materials, from Bell Labs,are also usable to filter the liquid. Nanograss controls the behavior oftiny liquid droplets by applying electrical charges to speciallyengineered silicon surfaces that resemble blades of grass. Additionally,or alternatively, the gas permeable, liquid impermeable materialsdisclosed in commonly owned, co-pending U.S. patent application Ser. No.10/356,793 are also usable in the present invention, all of which areincorporated herein by reference in their entireties.

Valve 36 is preferably a shut-off valve and can be any valve that iscapable of transporting the produced gas to a desired location, such asa fuel cell. Valve 36 is opened when hydrogen gas is needed, and valve36 is closed when there is no demand for hydrogen gas. Valve 36 can alsobe manually controlled by a user or automatically controlled by a CPU orcontroller, as needed. Valve 36 can be a check valve, a duckbill valve,a solenoid valve, magnetic valve, and other mechanical and/or electricalvalves. Suitable shut-off valves usable in the present invention furtherinclude the shut-off valves disclosed in commonly owned, co-pendingpatent application Ser. Nos. 10/978,949, filed on Nov. 1, 2004, and10/629,006, filed on Jul. 29, 2003. The disclosures of these referencesare incorporated herein by reference in their entireties. Alternatively,valve 36 may stay open and another valve within the fuel cell or thedevice can be opened and closed to control the flow of hydrogen.

In this embodiment, the enlarged second end of conduit 18 is operativelyassociated with self-regulated flow control device 16. Except for flowcontrol device 16, reaction chamber 12 and reservoir 14 are isolatedfrom each other by partition 23. As illustrated in FIG. 1( a), flowcontrol device 16 includes a disk 26 biased by spring 22. Both disk 26and spring 22 are enclosed by partition 23. Disk 26 is movable relativeto partition 23 and forms a seal therewith. Seal 21, e.g., o-ring, canbe incorporated in disk 26, as shown, to provide the seal. Preferably,disk 26 includes at least a substantially impermeable surface thatsupports the enlarged second end of conduit 18, or disk 26 can be madefrom substantially impermeable material(s).

In an operative or flow state, the enlarged second end conduit 18 isconnected to or is in contact with wicking layer 24 to establish a flowchannel, and the second reactant from reservoir 14 is transported bywicking or capillary action into reaction chamber 12 to react to formhydrogen gas. The production of gas increases the pressure insidereaction chamber 12. The increased gas pressure applies a force on disk26 against biasing spring 22, since disk 26 is substantially impermeableto gas and conduit 18, when wet with the second reactant, is capable ofresisting the gas from traveling down conduit 18. Furthermore, seal 21resists the fingering and/or leaking of hydrogen gas around disk 26.Hence, the gas pressure when valve 36 is closed acts on movable disk 26.At or above a predetermined pressure, the gas pressure within reactionchamber 12 separates disk 26 and the enlarged second end of conduit 18from wicking layer 24 creating a space 37, as shown in FIG. 1( b). Theseparation of conduit 18 from wicking layer 24 breaks the capillary flowpath and stops the transport of the second reactant.

When hydrogen gas is needed, valve 36 is opened manually,electronically, or automatically, the gas pressure in reaction chamber12 is released. Once the pressure in reaction chamber 12 decreases belowthe predetermined pressure, spring 22 pushes disk 26 and the enlargedsecond end of conduit 18 into contact with wicking layer 24 to restartthe flow of the second reactant into reaction chamber 12 and hydrogenproduction. When hydrogen gas is no longer needed, valve 36 is closedand the pressure inside reaction chamber 12 increases until reaching thepredetermined pressure, whereby this elevated pressure separates theenlarged second end of conduit 18 from disk 24 to stop the flow of thesecond reactant into the reaction chamber thereby stopping hydrogenproduction.

Thus, flow control device 16 is self-regulated such that in an operativestate or ON position, the first end of conduit 18 is spring-based intocontact with reaction chamber 12 to transport the second reactant intothe reaction chamber 12 by wicking or capillary action. In anon-operative state or OFF position, the pressure in reaction chamber 12above the predetermined pressure separates conduit 18 from reactionchamber 12 to stop the flow of the second reactant into reaction chamber12 and to stop the production of hydrogen.

To minimize the buildup of partial pressure in reservoir 14 and inaddition to the venting devices described above, baffle 140, which is aventing mechanism that allows the hydrogen gas from reaction chamber 12to enter reservoir 14, can be provided around conduit 18. An exemplarysuitable venting mechanism is fully described in commonly owned U.S.Pat. No. 5,906,446 directed to a writing instrument. The '446 patentteaches a venting mechanism that allows air to enter the ink reservoirto minimize vacuum buildup, while keeping the ink from flowing throughthe venting mechanism. The '446 patent is incorporated by referenceherein in its entirety.

As shown in the figures of the '446 patent and reproduced partiallyherein as FIG. 11, baffle 140 surrounds the wicking element andcomprises a plurality of ribs 142, 144, 146, 148, et seq. The spacingbetween these ribs is decreasing in the direction from reaction chamber12 toward reservoir 14. More specifically, ribs 142 located closer toreaction chamber 12 have relatively larger spacing than the next set ofribs 144, and ribs 144 have spacing that is relatively larger than thespacing in ribs 146 which are closer to reservoir 14, and so on. Anynumber of sets of ribs can be used and the present invention is notlimited to any particular sets of ribs.

This arrangement allows hydrogen to communicate from reaction chamber 12into reservoir 14, but does not allow reactant to flow from reservoir 14to reaction chamber, when a partial vacuum of a predetermined level ispresent in reservoir 14. As discussed above, the flow of reactant iscontrolled through conduit 18, which as shown can comprise two or moredifferent wicking materials.

An alternate self-regulated flow control device 16 is illustrated inFIGS. 1( c) and 1(d). The self-regulated flow control device has housing32 that includes movable member 30 biased by spring 28. Housing 32, atone end, is connected to reaction chamber 12 by pressure inlet port 34so that the pressure in reaction chamber 12 is communicated throughinlet channel 34 and acts on movable member 30 against the biasingforce.

Movable member 30 preferably includes a portion of the conduit 18therein, as illustrated in FIGS. 1( c) and 1(d) and labeled as 19. Whenthe pressure in reaction chamber 12 is less than the predeterminedpressure, spring 28 is sized and dimensioned to push and at leastpartially align member 30 so that at least a partial flow path isestablished. Hence, in an operative state or ON position the force ofspring 28, at least partially, aligns section 19 with conduit 18 to forma continuous capillary flow path between the first end of conduit 18 andthe enlarged second end of conduit 18. The second reactant in reservoir14 can flow from the first end of conduit 18 to the second end ofconduit 18 and into reaction chamber 12 to react and produce hydrogen.

When pressure in reaction chamber 12 exceeds the predetermined value, asillustrated in FIG. 1( c), the pressure communicates to movable member30 via port 34 and displaces member 30 against spring 28, so thatsection 19 is no longer aligned with conduit 18. Hence, in thenon-operative state or OFF position, this misalignment stops the flow ofthe second reactant into reaction chamber 12. Similar to the embodimentillustrated in FIGS. 1( a) and 1(b), when valve 36 is opened thepressure in reaction chamber 12 decreases. The relief of the pressureallows spring 28 to move section 19 within member 30 to align at leastpartially with conduit 18 to re-start the flow of the second reactantinto reaction chamber 12. Optional seals can be provided between movablemember 30 to separate conduit 18 from section 19 in the OFF position,between conduit 18 and spring 28 or between conduit 18 and pressure port34.

As illustrated in FIGS. 1( a) and 1(b), the first reactant is shown assolid. However, the first reactant can be in aqueous or liquid form.Additives such as stabilizers, catalysts or other additives can be mixedor blended with either the first or second reactants or both. Solidreactant includes, but is not limited to, powder, pellets, porousstructures, spheres, tubes, soluble sheaths or combinations thereof. Thepresent invention is not limited to any particular fuel or additives orhow the additives are mixed, blended, or stored in the gas-generatingapparatus.

In another embodiment illustrated in FIG. 2( a), gas-generatingapparatus 40 includes self-regulated flow control device 16, which has aself-regulated gas pressure control device 42 or gas valve 42 and aself-regulated liquid control device 41 or liquid valve 41. Flow controldevice 16 connects reservoir 14 to reaction chamber 12. Reservoir 14 caninclude a bladder or liner 44 holding the second reactant. Bladder 44can be made from any material, including flexible material or elasticmaterial. Suitable bladders are disclosed in commonly owned, co-pendingapplication Ser. No. 10/629,004, the disclosure of which is incorporatedherein by reference in its entirety. Alternatively, instead of bladder44 reservoir 14 can have any member that can separate the pressurizationfrom the second reactant, such as a movable wall forming a seal withreservoir 14 or an extensible liner adapted to receive the pressurizedgas. Similar to the embodiments described above, reaction chamber 12 mayalso have wicking layer 46 (similar to wicking layer 24) to improve thedistribution of the second reactant in reaction chamber 12. Reactionchamber 12 may also have a filler disk 48 made of wicking material or aliquid impermeable, gas permeable membrane (similar to membrane 25) todefine a separate gas collecting chamber 50. Valve 36 is provided totransport the hydrogen gas from chamber 50 or from reaction chamber 50to a fuel cell. Disk 48 may be connected to optional rod 47 made fromsimilar material for support or to distribute the second reactantthrough a column of first reactant. As illustrated in FIGS. 2( b)-2(d),first reactant does not necessarily have pellet form, but may be formedinto zig zag-shaped wafers, linear wafers, or grid-shaped wafers,respectively. Additionally, gas-generating apparatus 40 may includespray attachment 39, as illustrated in FIGS. 2( b)-2(d), to evenlydistribute the second reactant onto the first reactant wafers.

Self-regulated flow control device 16 allows the second reactant toenter reaction chamber 12 under certain conditions. Preferably,self-regulated flow control device 16 comprises gas valve 42 and liquidvalve 41 connecting bladder 44 containing the second reactant toreaction chamber 12 containing the first reactant. Initially, aftergas-producing apparatus 40 is constructed, reservoir 14 is pressurizedso that a small amount of second reactant is transported into reactionchamber 12 to start the reaction to produce hydrogen gas. As thepressure inside reaction chamber 12 increases, it equalizes the pressurein reservoir 14. When the pressures in these two compartments are withina predetermined difference, e.g., X psi, gas valve 42 opens to equalizethe pressures within these two compartments. When these two pressuresare substantially equal, i.e., within X psi of each other, the pressureapplied to bladder 44 cannot open liquid valve 41, and no flow of thesecond reactant occurs. Hence, gas producing apparatus 40 is in thenon-operative state or OFF position when reaction chamber 12 ispressurized. In one example, X psi is a predetermined value that can befrom about 1 psi to about 20 psi, preferably X can be about 5 psi, andmore preferably X can be about 2 psi.

When hydrogen is needed, shut-off valve 36 opens and gas-producingapparatus 40 is in the operative or ON position. As the hydrogen gas istransported out of gas-collecting chamber 50 or reaction chamber 12, thepressure within reaction chamber 12 decreases. When the pressuredifference between reservoir 14 and reaction chamber 12 exceeds X psi,gas valve 42 closes thereby preserving the higher pressure in reservoir14. The preserved pressure in reservoir 14 is applied to bladder 44which opens liquid valve 41 and transport the second reactant intoreaction chamber 12 to react with the first reactant.

Once the preserved higher pressure in reservoir 14 is bled off, thepressures in the two chambers are again within X psi. The produced gasin reaction chamber 12 opens gas valve 42 until the pressure fromreaction chamber 12 equalizes to the pressure in reservoir 14 and closesliquid valve 41 to stop the flow of the second reactant and thereby thereaction. To continue the reaction to produce hydrogen, shut-off valve36 is closed, preferably before all of the preserved higher pressure inreservoir 14 is bled off and while the pressures are within X psi ofeach other. This closure allows both chamber 12 and reservoir 14 tore-pressurize (since gas valve 41 remains open). Once the pressure hasreached a desired level, valve 36 is re-opened to start the cycle again.The opening and closing of valve 36 is cyclical and can be controlled bya CPU or a controller. A pressure gage can be inserted intogas-producing apparatus 40 and is readable by the CPU/controller tocontrol the open/close cycle. An exemplary operating cycle ofgas-generating apparatus 40 is summarized below.

TABLE 1 Operation by Cycling Valve 36 Liquid Gas valve 41 valve 42 P₁₂vs. P₁₄ Valve 36 Initial setting Close Close P₁₂ = P₁₄ Close Open valve36 Open Close P₁₂ < P₁₄ Open Hydrogen produced Close Open P₁₂ > P₁₄Close Open valve 36 Open Close P₁₂ < P₁₄ Open Hydrogen produced CloseOpen P₁₂ > P₁₄ Close Cycle repeats . . . until hydrogen demand isterminated and valve 36 is closed.

Alternatively, to maintain the production of hydrogen without cyclingshut-off valve 36, bladder 44 in reservoir 14 can be continuouslypressurized for example by compressed gas. Preferably, reservoir 14 hasa sufficient amount of liquefied hydrocarbon, such as N-butane,isobutane, or an isobutane and propane blend. The liquid-gas phasediagram of these materials is such that as long as some of thehydrocarbon remains in liquid form, its pressure is constant. In oneexample, the pressure within reservoir 14 is maintained at 17 psi (usingN-butane at room temperature) and when the pressure in reaction chamber12 reaches within or greater than X psi of 17 psi, gas valve 42 opens toequalize the pressure and no significant pressure differential acrossliquid valve 41 exists to open it; therefore, no flow occurs. Whenhydrogen gas is needed, valve 36 opens and the pressure differentialbetween the two chambers is more than X psi and gas valve 42 closes. Thepressure in reservoir 14 is then applied to bladder 44 to open liquidvalve 41 to transport the second reactant to reaction chamber 12 untilvalve 36 is closed. To minimize or prevent the pressurizing gas inreservoir 14 from entering reaction chamber 12, gas valve 42 can be aone-way valve, i.e., only allowing hydrogen gas from reaction chamber 12to enter reservoir 14. Also, when reservoir 14 is pressurized, gas valve42 can be omitted and the varying pressure differentials betweenreservoir 14 and reaction chamber 12 are sufficient to open and closeliquid valve 41. This embodiment is discussed further below and inreference to FIG. 5( a). Also, a microporous membrane can be positionedadjacent to gas valve 42. Suitable microporous membranes should havepore size large enough to allow the smaller hydrogen molecules to passthrough while small enough to block the larger hydrocarbon molecules.

Alternatively, isobutane or isobutane/propane blend can be used insteadof N-butane, which provides a pressure of about 31 psi and 50 psi,respectively. X psi can be any pressure, e.g., 2 psi, 4 psi, 6 psi, etc.

In another operating mode, the rate of hydrogen production in reactionchamber 12 is higher than the rate of hydrogen exiting shutoff valve 36.Hence, when valve 36 is in an open position, the pressure insidereaction chamber 12 continues to increase to a pressure greater than thepressure in the reservoir 14. When the pressure in reaction chamber 12exceeds the pressure inside reservoir 14 by a predetermined value,liquid valve 41 is closed to stop the second reactant from enteringreaction chamber 12 and gas valve 42 is opened to allow the pressureinside the reaction chamber 12 to be at least substantially equal to thepressure inside reservoir 14. Given that the hydrogen is in continuousdemand, the pressure inside reaction chamber 12 reduces to a pressureless than the pressure in reservoir 14, which results in gas valve 42closing and liquid valve 41 opening. A summary of this operating mode isillustrated in Table 2 below.

TABLE 2 Operation without Cycling Valve 36 and Pressurizing Reservoir 14Liquid Gas valve 41 valve 42 P₁₂ vs. P₁₄ Valve 36 Initial setting CloseClose P₁₂ = P₁₄ Close Open valve 36 Open Close P₁₂ < P₁₄ Open Hydrogenproduced at a Close Open P₁₂ > P₁₄ Open rate greater than required OpenClose P₁₂ < P₁₄ Open

In practice, gas-generating apparatus 40 may operate by the operatingmode illustrated in Table 2 when it is relatively new, i.e., when theapparatus is new and the reaction rate is relatively high. When thereactants are near depletion and the reaction rate falls below a certainrate, gas-generating apparatus may operate by the operating cycleillustrated in Table 1.

Gas-generating apparatus 40 may further include a relief valve 43. Thepurpose of relief valve 43 is to prevent having excess pressure build upin reaction chamber 12. For instance, relief valve 43 can be a valvethat is capable of opening once the pressure in reaction chamber 12reaches a predetermined value. Preferably, relief valve 43 is a checkvalve. Alternatively, relief valve 43 can manually be opened to ventsome of the hydrogen in hydrogen storage area 50. Membrane 25 can beused with relief valve to prevent liquid from leaving apparatus 40.

As illustrated in FIG. 3, an optional starter 52 can be included ingas-generating apparatus 40. Starter 52 can apply an initial pressure onbladder 44 to introduce the second reactant into reaction chamber 12 tostart a reaction. Starter 52 can be any type of starter known to oneskilled in the art. It can be a manual starter or an automatic starterthat is capable of starting an initial reaction once the gas-generatingapparatus is connected to an instrument that demands the generated gas.For example, starter 52 can be a button, a pumping mechanism, a slidingmechanism, and/or a screw that can be pressed, moved, or rotated toprovide a direct or indirect pressure on bladder 44 to introduce atleast some of the second reactant into reaction chamber 12. Exemplarystarters are also illustrated in FIGS. 8( a)-8(d).

Referring to FIGS. 4( a)-4(c), self-regulating flow control device 16may comprise diaphragm 56, which is adapted to cover opening 54 ofbladder 44 to stop the flow of the second reactant or to uncover opening54 to allow the flow of the second reactant into reaction chamber 12.Diaphragm 56 responds to the pressure differentials between reservoir 14and reaction chamber 12. As illustrated, reservoir 14 is pressurized bya compressed gas, spring, foam, liquefied hydrocarbon, or otherpressurizing mechanism to provide a substantially constant pressure onbladder 44. Initially, before first use, due to the higher pressure inreservoir 14, an amount of the second reactant is transported throughopening 54 and holes 55 on diaphragm 56 to react with the firstreactant. The produced hydrogen pressurizes reaction chamber 12 untilthe pressure in reaction chamber 12 is within X psi from the pressure inreservoir 14. Diaphragm 56 is sized and dimensioned so that within Xpsi, it closes opening 54, as shown in FIG. 4( c) and stops the flow ofthe second reactant. When hydrogen gas is needed, shut-off valve 36opens and the pressure in reaction chamber 12 decreases. Diaphragm 56opens, as shown in FIG. 4( b), allowing flow of the second reactant intoreaction chamber 12 to produce hydrogen on demand. When hydrogen is nolonger needed, valve 36 is shutoff and reaction chamber 12re-pressurizes to stop flow.

Referring to FIG. 5( a), diaphragm 56 can be replaced by check valve 57which opens and closes under the same conditions as diaphragm 56. FIG.5( b) illustrates a flow regulator 58. Preferably, regulator 58 is madefrom a filler material that has the capability of absorbing the secondreactant. As such, any material capable of absorbing the second reactantcan be utilized in the present invention. Suitable materials includefoam, fillers or fibrous materials. Other options include, but are notlimited to, the use of recovering valve and atomization restriction.

As illustrated in FIG. 6, gas-generating apparatus 40 can include astarter 64 connected to a valve 65 and a movable member or piston 68.Starter 64 can be pushed to open valve 65 to introduce the secondreactant into reaction chamber 12 to start the reaction. Starter 64 canbe a manual starter or an automatic starter capable of starting aninitial reaction once gas-generating apparatus 40 is connected to adevice that demands the generated hydrogen gas. Movable member 68 alsoincludes an optional valve 69. When optional valve 69 is used in thepresent invention, starter 64 can be used to start the initial reaction.Once the initial reaction starts and reaction chamber 12 is pressurized,this pressure is applied to piston 68 tending to open optional valve 69to allow the flow of the second reactant into reaction chamber 12.

To create a seal between movable member 68 and the wall(s) ofgas-generating apparatus 40, and to separate the second reactant fromthe first reactant, movable member 68 may have one or more seals 62,such as an o-ring. Furthermore, to compensate for the friction betweenmovable member 68 and the wall(s) of gas-generating apparatus 40,optional spring(s) 66 can be located in reaction chamber 12, as shown inFIG. 6.

Once the reaction starts, the pressure in reaction chamber 12 increasesto a predetermined level, such that the pressure in reaction chamber 12closes valve 69 to stop the flow of the second reactant coming intoreaction chamber 12. To minimize the vacuum developing in reservoir 14and to apply and/or maintain a pressure on the second reactant, movablemember 68 is biased toward reservoir 14 by spring 66. After the pressurein reaction chamber 12 is reduced by the opening of valve 36, the higherpressure in reservoir 14 opens valve 69 to transport additional secondreactant into reaction chamber 12 to produce more hydrogen.Alternatively, when optional valve 69 is not incorporated into movablemember 68, starter 64 can be pushed to open valve 65 and start the flowof the second reactant into reaction chamber 12 when needed.

Another embodiment is illustrated in FIG. 7. This embodiment is similarto FIG. 6, except that spring 66 is located in reservoir 14 and movablemember 68 does not include valve 69. Furthermore, starter 64 is replacedwith shaft 71 having a valve or ending 17 that is rotatable. Therotational movement of shaft 71 causes valve 17 to reciprocate linearly;thereby starting and stopping the flow of the second reactant intoreaction chamber 12. The valve system, as shown in FIG. 7, is generallyknown in the industry as a “linear control valve,” or a “globe valve.”Thus, to start the initial reaction shaft 71 is rotated to open valve17. The process of producing hydrogen in this embodiment is similar tothe process discussed in relation to FIG. 6. However, in thisembodiment, when member 68 is moved towards reservoir 14, the movementof member 68 rotates valve 17 connected to shaft 71 to stop the flow ofthe second reactant into reaction chamber 12. When the pressure inreaction chamber 12 is reduced below a predetermined pressure, spring 66pushes movable member 68 towards reaction chamber 12, which, in turn,rotates and opens valve 17 connected to shaft 71.

FIG. 8( a) illustrates another embodiment of the present invention. Inthis gas-generating apparatus, reaction chamber 12 is separated fromreservoir 14/bladder 44 by movable piston 68. However, reaction chamber12 is in constant fluid communication with reservoir 14 through opening72 defined on piston 68. Movable piston 68 is also biased towardreservoir 14 by spring 66 located within reaction chamber 12. To startthe reaction, starter 74 is activated, e.g., by pushing. The pressurecreated by the activation of starter 74 opens check valve to release thesecond reactant into reaction chamber 12 to react with the firstreactant. Hydrogen gas is produced which pressurizes the entiregas-generating apparatus. When valve 36 is opened, hydrogen gas isreleased. Since there is no pressure differential between reservoir 14and reaction chamber 12, nothing stops the flow of the second reactantinto reaction chamber 12. Therefore, hydrogen is produced until all thereactants are spent.

FIGS. 8( b)-8(d) illustrate other types of starters. As illustrated inFIG. 8( b), push button 74 can be replaced with a pump button 82 thatcan fill a bladder 78 with a gas, such as air. Bladder 78 can place aforce on bladder 44 to introduce at least some or a predetermined amountof the second reactant into reaction chamber 12. Additionally, asillustrated in FIG. 8( c), push button 74 can be replaced with ascrew-type device 76 that can be turned to place a force on bladder 44.Other optional embodiments can include, for example, a sliding mechanismor sliding switch 84, as illustrated in FIG. 8( d). In this embodiment,when sliding switch 84 is moved in a predetermined direction, it canplace a force on bladder 44 to release some of or a predetermined amountof the second reactant into reaction chamber 12.

Another embodiment of the present invention is illustrated in FIGS. 9(a)-9(d). This gas-generating apparatus includes reaction chamber 12having a first reactant connected to reservoir 14 having a secondreactant through self-regulated flow control device 16. Reservoir 14 andbladder 44 can be removably connected to control device 16. Whenreservoir 14 is removably connected to control device 16, preferablybladder 44 has a check valve to seal the bladder and conduit 45 has acorresponding check valve to seal the conduit and to mate with the checkvalve on bladder 44 to establish a flow path there between. Suitablecorresponding valve components are fully disclosed in U.S. patentapplication Ser. Nos. 10/629,006 and 10/978,949, which are incorporatedherein by reference in their entireties. Also preferably, reservoir 14is pressurized as discussed above, preferably with liquefiedhydrocarbon.

Self-regulating flow control device 16 comprises conduit 45/diaphragm 92interacting with or operatively associated with rod 94. Rod 94 isdisposed within conduit 45. In a non-operative or OFF position as bestshown in FIG. 9( c), rod 94 compresses seal 98 against sealing surface97 to prevent flow. Conduit 45, as illustrated, has several turns.However, the actual shape of the flow path is not important and thepresent invention is not limited to any particular shape for conduit 45.Preferably, seal 98 is under compression without a shear component toextend the life of seal 98. This can be accomplished by a non-angularsealing surface, such as sealing surface 97. In an operative or ONposition as best shown in FIG. 9( d), rod 94 and seal 98 are moved fromsealing surface 97 to allow flow therethrough. Seal 98 includes O-rings,wipers or any known sealing element.

Diaphragm 92 and rod 94 are balanced between optional upper spring 88and lower spring 96. These springs are pre-loaded to correspond to apredetermined pressure of reaction chamber 12, above which thegas-generating apparatus is closed. Optional adjuster 86 is provided toadjust the relative pre-load of the springs. As best shown in FIG. 9(b), a pressure P2 from reaction chamber is communicated back intoconduit 45 (hydraulically through the liquid second reactant or throughthe produced hydrogen). Pressure P2 acts on the bottom of diaphragm 92,and when P2 is sufficiently high, P2 pushes diaphragm 92 and rod 94upward to close the flow path of conduit 45. The pre-loadings of springs88 and 96 or the relative pre-loadings of these springs determine thepressure, at which P2 should reach before conduit 45 is shut-off.Alternatively, one of springs 88 and 96 can be omitted. For example,spring 96 can be omitted leaving spring 88 to counter-balance againstpressure P2 acting on diaphragm 92.

Similar to the other embodiments, reaction chamber 12 has valve 36, atleast one liquid impermeable, gas permeable membrane 25 covering theentrance thereof. Reaction chamber 12 also has at least onefiller/filter 46, at least one screen 110 that is capable of preventingor at least reducing the number of particles that enter the area ofdiaphragm 92, at least one diffusion mesh 114 to minimize the cloggingof the gas-generating apparatus, and at least one diffusion mesh 120,which prevents screen 110 from plugging. Optionally, gas-generatingapparatus 40 includes a gas impermeable member between bladder 44 andseal 98 to prevent any gas from entering bladder 44.

Another embodiment is illustrated in FIG. 10. In this embodiment,gas-generating apparatus 40, in addition to reservoir 14 and reactionchamber 12, includes chamber 126. Chamber 126 is separated from reactionchamber 12 by movable member 68, which has valve components 132 and 128disposed thereon. Preferably, gas permeable/liquid impermeable member 48is disposed between valve components 132 and 128 to retain liquids inreaction chamber 12 while allowing any produced gas to pass out ofreaction chamber 12. Chamber 126 further comprises male valve 130, whichis adapted to connect to female valve 128.

Movable member 68 shuttles between shut-off valve 36 and reservoir 14.On one side, movable member 68 is biased by spring 66, and on the otherside it can be pushed by the gas produced in reaction chamber 12. Whenmovable member 68 is pushed toward shut-off valve 36, valve 130 connectsto valve 128 to transfer the gas from reaction chamber 12 to gas chamber50. When movable member 68 is pushed toward reservoir 14, valve 134connects to valve 132 to transfer additional second reactant fromreservoir 14 to reaction chamber 12.

Preferably, prior to the first use, reaction chamber 12 includes apressurized gas, such as inert gases, air or hydrogen. The gaspressurizes reaction chamber 12 to a level approaching the predeterminedpressure that pushes movable member 68 for a distance that enablesfemale valve 128 be suitably in contact with male valve 130. Whenproduction of hydrogen is required, valve 36 is opened to release thestored gas. This release reduces the pressure in gas chamber 50 and alsoin reaction chamber 12. When the pressure in reaction chamber 12 fallsbelow a predetermined level, spring 66 pushes movable member 68 towardsreservoir 14. Preferably, spring 66 pushes movable member 68 for adistance sufficient to insert male valve 132 into female valve 134. Theinsertion of male valve 132 into female valve 134 opens a pathway sothat the second reactant in reservoir 14 can flow into reaction chamber12 via orifices 49. Once the second reactant is introduced into reactionchamber 12, it reacts preferably with the first reactant to producehydrogen. The produced hydrogen increases the pressure in reactionchamber 12. When the pressure reaches a predetermined value or exceedsthe pressure exerted on movable member 68 by spring 66, movable member68 is pushed towards male valve 130. The connection of male valve 130with female valve 128 opens a path for the produced hydrogen to exitreaction chamber 12 into chamber 50 and then out of gas-generatingapparatus 40 via valve 36.

The cycle then repeats and movable member 68 is again moved towardsreservoir 14 to connect valve 134 to valve 132 to transport additionalsecond reactant into reaction chamber 12. Preferably, reservoir 14 ispressurized and the second reactant is stored in bladder 44, asdiscussed above.

In each of the embodiments described above, gas-generating apparatus 40includes a reaction chamber 12 and a reservoir 14. In some exemplaryembodiments, the first reactant in reaction chamber 12 and/or the secondreactant in reservoir 14 or bladder 44 can include at least one of anoptional catalyst, a hydrogen bearing fuel, an agent (e.g., water) thatcan react with the hydrogen bearing fuel in the presence or absence ofthe catalyst to produce a gas, and optionally an additive. Preferably,the agent can react with the hydrogen bearing fuel in the presence of acatalyst to create the desired gas. Preferably, the first reactant inreaction chamber 12 and the second reactant in reservoir 14 or bladder44 should not have the same composition. More preferably, hydrogenbearing fuel and the agent are in separate chambers. That is, if thefirst reactant in reaction chamber 12 includes the hydrogen bearingfuel, then it is preferable to have the agent as the second reactant inreservoir 14.

The hydrogen bearing fuel of the present invention can be any fuelcapable of producing a gas, such as hydrogen, when reacted with anagent/composition, and/or placed under certain conditions. In someexemplary embodiments, the hydrogen bearing fuel can include a metalhydroxide. In some exemplary embodiments, the fuel can include, but isnot limited to, hydrides of elements of Groups I-III of the PeriodicTable of the Elements and mixtures thereof, such as, for example,alkaline or alkali metal hydrides, or mixtures thereof. Other compounds,such as alkali metal-aluminum hydrides (alanates) and alkali metalborohydrides may also be employed. For example, calcium hydride may beutilized as the solid fuel for such use in accordance with theinvention. Preferably, the hydrogen bearing fuel includes NaBH₄, whichcan be in a solid state. However, aqueous NaBH₄ can also be utilized inthe present invention. Preferably, when an aqueous form of NaBH₄ isutilized, the chamber containing the aqueous NaBH₄ also includes astabilizer. Exemplary stabilizers can include, but are not limited to,metal hydroxides, such as, for example, alkali metal hydroxides. Mostpreferably, the stabilizer is NaOH.

In some exemplary embodiments, the first reactant, the second reactant,or both can include a catalyst that can facilitate the production ofhydrogen gas by increasing the rate of reaction of the fuel source. Thecatalyst of the present invention can include any shape or size that iscapable of promoting the desired reaction. For example, the catalyst canbe small enough to form a powder or can be as large as the reservoir orthe reaction chamber. In some exemplary embodiments, the catalyst is acatalyst bed. The optional catalyst can be located inside the reactionchamber, inside the reservoir, inside the bladder, proximate to thereaction chamber, the reservoir, or the bladder, as long as at least oneof either the first reactant or the second reactant comes into contactwith the catalyst.

In some exemplary embodiments, the catalyst can include a rutheniumcatalyst, a platinum catalyst, a nickel catalyst, or any other catalystknown to one skilled in the art. In some exemplary embodiments,catalysts having a metal from Group VIIIB of the Periodic Table of theElements can be used. Preferably, the catalyst that can be used withgas-generating apparatus 40 of the present invention is CoCl₂.

Some exemplary fuels that can be used in the present invention are, butnot limited to, methanol, borohydride, ammonia borane, and hydrazine. Tomake these exemplary fuels, the first precursor can be dimethyldicarbonate, water, borane-containing polymer, carbonate, ammonia,azine, and/or hydrogen peroxide. Each of these fuels is described indetail in U.S. patent application Ser. No. 10/854,540, which ispreviously incorporated herein in its entirety.

In some exemplary embodiments, the agent capable of reacting with thefuel is water. Preferably, the first reactant of the present invention,which, preferably, is located in the reaction chamber, is NaBH₄ and thesecond reactant, which, preferably, is located in the reservoir or thebladder in the reservoir, is water.

In some exemplary embodiments, the optional additive, which can be inthe reaction chamber, in the reservoir, and/or in the bladder, can beany composition that is capable of substantially preventing freezing ofor reducing the freezing point of the first and/or second reactant. Insome exemplary embodiments, the additive can be an anti-freezing agent.In some exemplary embodiments, the additive can be an alcohol-basedcomposition. Preferably, the additive of the present invention is CH₃OH.However, as stated above, any additive capable of reducing the freezingpoint of the first and/or second reactant can be used.

The aqueous solution optionally includes an acid having a pH of fromabout 3-5. An example of an acid that is added to the aqueous solutionis acetic acid. One purpose of the acid in the present invention is toallow a more constant reaction between the aqueous solution and thesolid fuel by preventing the formation of a barrier at the entrance ofthe reaction chamber.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the present specification andpractice of the present invention disclosed herein. It is intended thatthe present specification and examples be considered as exemplary onlywith a true scope and spirit of the invention being indicated by thefollowing claims and equivalents thereof.

We claim:
 1. A gas-generating apparatus comprising: a reaction chamber,a reservoir comprising at least one liquid reactant, and a flow controldevice comprising a flow channel adapted to transport the liquidreactant to the reaction chamber to react to generate gas and adiaphragm adapted to move from a first position to a second position inresponse to pressure, wherein the transport of the liquid reactant isallowed when the diaphragm is in the first position and wherein thetransport of the liquid reactant is stopped when the diaphragm is in thesecond position, and wherein the diaphragm is spaced apart from the flowchannel.
 2. The gas-generating apparatus of claim 1, wherein said atleast one liquid reactant flows along the surface of the diaphragm whenthe diaphragm is in the first position.
 3. The gas-generating apparatusof claim 1, wherein the pressure is a pressure of the reaction chamber.4. The gas-generating apparatus of claim 1, further comprising a sealingmember operatively connected to the diaphragm to seal the flow path inthe second position.
 5. The gas-generating apparatus of claim 1, furthercomprising a rod operatively connected to the diaphragm.
 6. Thegas-generating apparatus of claim 4, further comprising at least aspring supporting the diaphragm and to the sealing member.
 7. Thegas-generating apparatus of claim 1, wherein the diaphragm is supportedby opposing springs.
 8. A gas generating apparatus comparing a reactionchamber, a reservoir comprising at least one liquid reactant, and a flowcontrol device comprising a flow channel adapted to transport the liquidreactant to the reaction chamber and a diaphragm adapted to move from afirst position to a second position in response to pressure, wherein inthe first position the diaphragm closes the flow channel and wherein inthe second position the diaphragm moves away from the flow channel andthe liquid reaction is transported through the flow channel through anopening in the diaphragm to the reaction chamber.
 9. The gas-generatingapparatus of claim 8, wherein the pressure is a pressure of the reactionchamber.
 10. The gas-generating apparatus of claim 8, wherein thereaction chamber comprises a second reactant.